package org.apache.lucene.store;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.net.ServerSocket;
import java.net.Socket;
import java.io.OutputStream;
import java.io.InputStream;
import java.io.IOException;

/**
 * Simple standalone server that must be running when you use
 * {@link VerifyingLockFactory}. This server simply verifies at most one
 * process holds the lock at a time. Run without any args to see usage.
 * 
 * @see VerifyingLockFactory
 * @see LockStressTest
 */

public class LockVerifyServer {

	private static String getTime(long startTime) {
		return "[" + ((System.currentTimeMillis() - startTime) / 1000) + "s] ";
	}

	public static void main(String[] args) throws IOException {

		if (args.length != 1) {
			System.out
					.println("\nUsage: java org.apache.lucene.store.LockVerifyServer port\n");
			System.exit(1);
		}

		final int port = Integer.parseInt(args[0]);

		ServerSocket s = new ServerSocket(port);
		s.setReuseAddress(true);
		System.out.println("\nReady on port " + port + "...");

		int lockedID = 0;
		long startTime = System.currentTimeMillis();

		while (true) {
			Socket cs = s.accept();
			OutputStream out = cs.getOutputStream();
			InputStream in = cs.getInputStream();

			int id = in.read();
			int command = in.read();

			boolean err = false;

			if (command == 1) {
				// Locked
				if (lockedID != 0) {
					err = true;
					System.out.println(getTime(startTime) + " ERROR: id " + id
							+ " got lock, but " + lockedID
							+ " already holds the lock");
				}
				lockedID = id;
			} else if (command == 0) {
				if (lockedID != id) {
					err = true;
					System.out.println(getTime(startTime) + " ERROR: id " + id
							+ " released the lock, but " + lockedID
							+ " is the one holding the lock");
				}
				lockedID = 0;
			} else
				throw new RuntimeException("unrecognized command " + command);

			System.out.print(".");

			if (err)
				out.write(1);
			else
				out.write(0);

			out.close();
			in.close();
			cs.close();
		}
	}
}
